Laboratory flask

In chemistry, or general laboratory bulbous vessels (usually glass vessels) called pistons. Size, shape, and material (for example: glass, borosilicate glass, PE, TEFLON) vary depending on the application. Piston, used for distilling or for heating liquids, are usually made of heat resistant borosilicate glass.

The picture shows from left to right, two different sized flasks (flat bottom, adjusted to specific volumes, used for example for the preparation of standard solutions ), an Erlenmeyer flask (flat bottom and on the neck, for example, for the titration ), a three-necked flask ( reactor ) and a rotary evaporation flask (for evaporation of liquids at elevated temperature and vacuum). There are also many other embodiments of Flask: Flat bottom ( similar to a round bottom flask, but with a flat bottom ), pear or Walter flask, Kjeldahl flask ( use in the analysis for the determination of nitrogen by the Kjeldahl method ), two-necked flask and three-necked flask ( use in the synthesis) and shaped flask ( to be used as collection vessels under a spider). Most of these pistons are provided with a standard ground, so that a simple installation in complex glass apparatus is possible.

In electrical engineering provides a piston, the separation between the familiar to humans gas mixtures of the Earth's atmosphere and a special, produced for the specific application environment inside the flask (vacuum, air, vapor or gas filled with noble gases of low pressure, such as mercury vapor) ago. Usually these are made of glass, or ceramic, rare metal (steel). The materials must be sufficiently gas tight and mechanical loads withstand ( Druckunterschied! ). Electrical connections are made by means of melted or isolated guided by guide wires. Example: pinch. The term piston is shown very clearly in incandescent lamps, electron tubes older cathode ray tubes and mercury arc rectifiers by their often bulbous shape.